From: David Laight <David.Laight@ACULAB.COM>
To: 'Cyrill Gorcunov' <gorcunov@gmail.com>, Joel Savitz <jsavitz@redhat.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
"Masami Hiramatsu" <mhiramat@kernel.org>,
Waiman Long <longman@redhat.com>,
"Mauro Carvalho Chehab" <mchehab+samsung@kernel.org>,
Kristina Martsenko <kristina.martsenko@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Kees Cook <keescook@chromium.org>,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
YueHaibing <yuehaibing@huawei.com>,
Micah Morton <mortonm@chromium.org>,
Yang Shi <yang.shi@linux.alibaba.com>,
Jann Horn <jannh@google.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Rafael Aquini <aquini@redhat.com>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Yury Norov <norov.maillist@gmail.com>
Subject: RE: [PATCH v2 1/2] kernel/sys: add PR_GET_TASK_SIZE option to prctl(2)
Date: Fri, 3 May 2019 11:31:40 +0000 [thread overview]
Message-ID: <6cf43408000149d98cc1683943c436cb@AcuMS.aculab.com> (raw)
In-Reply-To: <20190503083149.GH2488@uranus.lan>
From: Cyrill Gorcunov
> Sent: 03 May 2019 09:32
> On Thu, May 02, 2019 at 05:46:08PM -0400, Joel Savitz wrote:
> > > Won't be possible to use put_user here? Something like
> > >
> > > static int prctl_get_tasksize(unsigned long __user *uaddr)
> > > {
> > > return put_user(TASK_SIZE, uaddr) ? -EFAULT : 0;
> > > }
> >
> > What would be the benefit of using put_user() over copy_to_user() in
> > this context?
>
> It is a common pattern to use put_user with native types, where
> copy_to_user more biased for composed types transfer.
It also removes all the crappy code that checks whether the
kernel buffer is valid.
David
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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2019-05-03 11:31 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-02 20:52 [PATCH v2 0/2] sys/prctl: expose TASK_SIZE value to userspace Joel Savitz
2019-05-02 20:52 ` [PATCH v2 1/2] kernel/sys: add PR_GET_TASK_SIZE option to prctl(2) Joel Savitz
2019-05-02 21:09 ` Cyrill Gorcunov
2019-05-02 21:46 ` Joel Savitz
2019-05-03 8:31 ` Cyrill Gorcunov
2019-05-03 11:31 ` David Laight [this message]
2019-05-02 21:24 ` Rafael Aquini
2019-05-02 21:49 ` Yury Norov
2019-05-02 20:52 ` [PATCH v2 2/2] prctl.2: Document the new PR_GET_TASK_SIZE option Joel Savitz
2019-05-02 22:23 ` Yury Norov
2019-05-03 1:49 ` Rafael Aquini
2019-05-02 21:01 ` [PATCH v2 0/2] sys/prctl: expose TASK_SIZE value to userspace Waiman Long
2019-05-02 21:10 ` Cyrill Gorcunov
2019-05-02 21:22 ` Joel Savitz
2019-05-02 21:34 ` Yury Norov
2019-05-02 21:26 ` Rafael Aquini
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